/* $Id: dsmixer.cpp,v 1.5 2001-04-20 13:22:38 phaller Exp $ */
/*
 * DirectSound Software Mixer
 *
 * Copyright 2000 Michal Necasek
 * Copyright 2000 Ondrej Necasek
 *
 * Project Odin Software License can be found in LICENSE.TXT
 *
 */


/*@Header***********************************************************************
*   Header Files                                                               *
*******************************************************************************/
#define INCL_DOSMISC
#include <os2win.h>

#include <stdlib.h>
#include <string.h>

#define CINTERFACE
#include <dsound.h>

#include "os2dsound.h"
#include "os2sndbuffer.h"
#include "os2notify.h"
#include <misc.h>

//@@@ signed long mixbuf[2300*2]; /* enough for 50 ms at 44100Hz stereo */


// The internal mixer buffer for sample calculations
// It's allocated on demand by MixFunc.
static signed long* mixbuf = NULL;   // pointer to the mixer data buffer
static ULONG ulMixerBufferSize = 0;        // current size of the mixer buffer


void MixCallback(ULONG cbMix) 
{
  // Check for priority level here; for DSSCL_WRITEPRIMARY just play directly
  // from the primary buffer; for all others mix the secondary buffers
  if (OS2IDirectSoundBuffer::primary->parentDS->GetCoopLevel() != DSSCL_WRITEPRIMARY)
    MixFunc(OS2IDirectSoundBuffer::dsbroot, OS2IDirectSoundBuffer::primary, cbMix);
  else 
  {
  }
}


void MixOneBuffer(OS2IDirectSoundBuffer *inBuf, int tomix, int outrate)
{
  unsigned char *data8b;
  signed short *data16b;
  int inpos, spd, i, j, sample, len, bytespersample, vol1, vol2;
  int oldpos;

  bytespersample = inBuf->lpfxFormat->wBitsPerSample *
    inBuf->lpfxFormat->nChannels / 8;
  inpos = inBuf->playpos / bytespersample * 1024 + inBuf->frac;
  spd = 1024 * inBuf->frequency / outrate;
  if (inBuf->pan <= 0)
    vol1 = inBuf->volume;
  else
    vol1 = inBuf->volume * (256 - inBuf->pan) / 256;
  if (inBuf->pan >= 0)
    vol2 = inBuf->volume;
  else
    vol2 = inBuf->volume * (256 + inBuf->pan) / 256;

  len = inBuf->bufferdesc.dwBufferBytes / bytespersample * 1024;
  if ((inBuf->lpfxFormat->nChannels == 2) && 
      (inBuf->lpfxFormat->wBitsPerSample == 16)) 
  {
    data16b = (signed short *) inBuf->lpBuffer;
    for (i = 0; i < tomix; i++) 
    {
      j = inpos / 1024 * 2;
      mixbuf[i*2] += data16b[j] * vol1 / 256;
      mixbuf[i*2+1] += data16b[j+1] * vol2 / 256;
      inpos += spd;
      if (inpos >= len) 
      {
        if (inBuf->fLoop) inpos -= len;
        else 
        {
          inBuf->fPlaying = FALSE;
          if (inBuf->notify != NULL)
            inBuf->notify->CheckStop();
          
          break;
        }
      }
    }
  }
  
  if ((inBuf->lpfxFormat->nChannels == 1) && 
      (inBuf->lpfxFormat->wBitsPerSample == 16)) 
  {
    data16b = (signed short *) inBuf->lpBuffer;
    for (i = 0; i < tomix; i++) 
    {
      j = inpos / 1024;
      sample = data16b[j];
      mixbuf[i*2] += sample * vol1 / 256;
      mixbuf[i*2+1] += sample * vol2 / 256;
      inpos += spd;
      if (inpos >= len) 
      {
        if (inBuf->fLoop) inpos -= len;
        else 
        {
          inBuf->fPlaying = FALSE;
          if (inBuf->notify != NULL)
            inBuf->notify->CheckStop();
          
          break;
        }
      }
    }
  }
  
  if ((inBuf->lpfxFormat->nChannels == 2) && 
      (inBuf->lpfxFormat->wBitsPerSample == 8)) 
  {
    data8b = (unsigned char *) inBuf->lpBuffer;
    for (i = 0; i < tomix; i++) 
    {
      j = inpos / 1024 * 2;
      sample = ((int) data8b[j] - 128) * vol1;
      mixbuf[i*2] += sample;
      sample = ((int) data8b[j+1] - 128) * vol2;
      mixbuf[i*2+1] += sample;
      inpos += spd;
      if (inpos >= len) 
      {
        if (inBuf->fLoop) inpos -= len;
        else 
        {
          inBuf->fPlaying = FALSE;
          if (inBuf->notify != NULL)
            inBuf->notify->CheckStop();
          
          break;
        }
      }
    }
  }
  
  if ((inBuf->lpfxFormat->nChannels == 1) && 
      (inBuf->lpfxFormat->wBitsPerSample == 8)) 
  {
    data8b = (unsigned char *) inBuf->lpBuffer;
    for (i = 0; i < tomix; i++) 
    {
      j = inpos / 1024;
      sample = (int) data8b[j] - 128;
      mixbuf[i*2] += sample * vol1;
      mixbuf[i*2+1] += sample * vol2;
      inpos += spd;
      if (inpos >= len) 
      {
        if (inBuf->fLoop) inpos -= len;
        else 
        {
          inBuf->fPlaying = FALSE;
          if (inBuf->notify != NULL)
            inBuf->notify->CheckStop();
          
          break;
        }
      }
    }
  }
  
  oldpos         = inBuf->playpos;
  inBuf->playpos = inpos / 1024 * bytespersample;
  inBuf->frac    = inpos % 1024;

  // Check if any notifications are to be signaled
  if (inBuf->notify != NULL)
    inBuf->notify->CheckPos(oldpos, inBuf->playpos);

  // keep the write cursor about 15ms ahead of the play cursor
  inBuf->writepos  = inBuf->playpos + inBuf->frequency * bytespersample / 67;
  inBuf->writepos %= inBuf->bufferdesc.dwBufferBytes;
}


void MixFunc (OS2IDirectSoundBuffer *firstBuf, 
              OS2IDirectSoundBuffer *outBuf,
              ULONG cbMix) 
{
  OS2IDirectSoundBuffer *inBuf = firstBuf;
  int i;
  int outbits;
  int outrate;
  int outnch;
  int tomix;
  int outpos;
  int outlen;
  unsigned char *data8b;
  signed short *data16b;

  outbits = outBuf->lpfxFormat->wBitsPerSample;
  outrate = outBuf->lpfxFormat->nSamplesPerSec;
  outnch = outBuf->lpfxFormat->nChannels;
  tomix = cbMix * 8 / outbits / outnch;
  
  // calculate required size (elements) of mixer buffer
  ULONG ulRequiredSize = tomix * outnch;
  
  // dynamically allocate the mixerbuffer as required
  if (ulMixerBufferSize < ulRequiredSize)
  {
    // check if buffer has been allocated at all
    if (NULL == mixbuf)
    {
      // allocate new buffer
      mixbuf = (signed long*) malloc(ulRequiredSize * sizeof(mixbuf[0]));
      ulMixerBufferSize = tomix;
    }
    else
    {
      // reallocate existing buffer
      mixbuf = (signed long*) realloc(mixbuf, ulRequiredSize * sizeof(mixbuf[0]));
      ulMixerBufferSize = tomix;
    }
  }
  
  
  /* PH 2001-04-20 PowerDVD 3 comes in with tomix==4096
   * (ulNumDartBuffers == 1.
   * So below memset() crashed as the former static 
   * mixer buffer was way to small. The dynamic allocation
   * is supposed to fix this.
   *
   * Also the assumption (?) of outnch == 2 is not met here.
   * PowerDVD tries with 4 channels, thus requiring an even
   * larger buffer.
   */
  memset(&mixbuf[0], 0, ulRequiredSize * sizeof(mixbuf[0]));

  
  while (inBuf != NULL) 
  {
    if (inBuf->fPlaying)
    {
      MixOneBuffer(inBuf, tomix, outrate);
    }
    inBuf = inBuf->next;
  }

  outpos = outBuf->playpos * 8 / outbits;
  outlen = outBuf->bufferdesc.dwBufferBytes * 8 / outbits;

  if (outbits == 16)
  {
    data16b = (signed short *) outBuf->lpBuffer;
    for (i = 0; i < tomix * outnch; i++) 
    {
      if (mixbuf[i] <= -32768) 
        data16b[outpos] = -32768;
      else 
        if (mixbuf[i] >= 32767) 
          data16b[outpos] = 32767;
        else 
          data16b[outpos] = (signed short)mixbuf[i];
      
      outpos++;
      
      if (outpos >= outlen) 
        outpos = 0;
    }
  } 
  else 
  {
    data8b = (unsigned char *) outBuf->lpBuffer;
    for (i = 0; i < tomix * outnch; i++) 
    {
      if (mixbuf[i] <= -32768) 
        data8b[outpos] = 0;
      else 
        if (mixbuf[i] >= 32767) 
          data8b[outpos] = 255;
        else 
          data8b[outpos] = (signed short)mixbuf[i] / 256 + 128;
      
      outpos++;
      if (outpos >= outlen) 
        outpos = 0;
    }
  }
  
  outBuf->playpos = outpos * outbits / 8;
}